The present invention relates to a mechanical arm strut, and more particularly, to a self-centering mechanical strut.
Gas springs or mechanical struts can be used to assist in the operation of earth-moving equipment, such as small loaders, tractors, excavators, harvesters, etc. The invention provides a self-centering mechanism that can be installed on existing transmission shifter arms for the purpose of imparting a spring return to a shifter arm in response to relative motion out of a predetermined neutral position. The self-centering strut can be used with a hydrostatic transmission such as for an agricultural tractor, a small loader, a harvester, etc. Hydrostatic transmissions tend to creep out of a neutral position unless restrained while the engine continues to run at an operating speed. Thus, the self-centering strut can be added which will exert a return force on the transmission shifter arm whenever it is moved out of neutral back into a neutral position. Such spring return devices typically consist of coaxial outer and inner tube members with elongated helical springs received in annular spaces within the members. When the shifter is in the neutral position, the springs are maintained in a partially compressed state by opposed sets of abutment stops or elements carried by the respective tube members. Longitudinal movement imposed on the tubes in either direction, such as shifting the transmission out of neutral into either forward or reverse gear positions, causes further compression of either spring.
The present invention employs a self-centering device using the mechanical struts and includes coaxial tubular members, springs, and associated stop elements.